[Dspforum] More Lab 5 Questions

[Joseph Haber]

Nenad,

If you keep having difficulty, send a copy of your code directly to me and Doug.

Joseph

On 10/12/09, Joseph Haber <josephhaber at gmail.com> wrote:
> Nenad,
>
> At least one problem is likely with the documentation of the length
> you should give when generating the bit_rev_index. It should be
> sqrt(8192*2) = 128, I believe.
>
> Joseph
>
>
>
> On 10/12/09, Nenad Uzunovic <nenad at roboticresearch.com> wrote:
>>
>> I am trying to use single-precision bit-reverse function and input with
>> (double *) is confusing me. From documentation, I understood that
>> (double *) stands for two floats i.e complex pair. Just like with two
>> shorts being an int in sample function. Common sense, right :)? #$%^@
>>
>> Though, I still get bogus data on the output. I read documentation in
>> fair detail and am not sure where more to go. I think I am passing all
>> the data right.
>>
>> By the way, documentation for cfft references functions that can be
>> found in
>> C:\CCStudio\c6700\dsplib\support\fft
>> that took me a while to figure out.
>>
>> In one of the forums online I found that someone was using
>> bit_rev(current_data, PROCESS_LENGTH);
>> instead of
>> DSPF_sp_bitrev_cplx((double*)current_data,
>>                      bit_rev_index,
>>                      PROCESS_LENGTH);
>> I tried it, and this time I did not get a bunch of NANs. Though I don't
>> think my plots are correct. I need to investigate this more.
>>
>> Can we get a little more information about usage of these tools?
>>
>> Thanks,
>> Nenad
>>
>>
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>>
>